INTRODUCTION
Dementia is a clinical syndrome characterized by declines in cognitive, psychological, and behavioral functions.1) Globally, the number of people with dementia is projected to nearly triple between 2019 and 2050.2) In 2023, the prevalence of dementia and mild cognitive impairment among Koreans aged 65 years and older was 9.3% and 28.4%, respectively.3) With an aging population, the health and economic burden of dementia is expected to increase further.4,5)
The burden of care for people with dementia falls primarily on family members. According to a 2023 nationwide survey in Korea, 45.8% of family members of community-dwelling dementia patients reported experiencing caregiver burden.3) Even family caregivers who do not live with the patient spend an average of 18 hours per week providing direct care, and an additional 10 hours using external care services.3) Family caregivers often face economic strain due to productivity loss associated with caregiving responsibilities.4)
Previous studies conducted in Korea suggest that caregiving for individuals with dementia can be detrimental to the mental health of informal caregivers.3,6,7) In particular, participants in the 2023 nationwide survey reported that caregiving for a family member with dementia adversely affected their psychological well-being, mental health, and quality of life.3) Family caregivers who live with a person with dementia are also at increased risk of perceived stress, depressive symptoms, and physician-diagnosed depression.6,7) The relationship between dementia diagnosis in older adults and depressive symptoms among their caregivers may be mediated by social isolation among primary caregivers.8)
Furthermore, previous studies suggest that caregiving for a family member with dementia may be associated with declines in the caregiver’s own cognitive function.9,10) For example, spouses of dementia patients have been found to be at elevated risk of developing incident dementia themselves compared with spouses of individuals without dementia.9) This increased risk among spousal caregivers appears to be mediated by psychosocial factors such as social isolation and depression, as well as behavioral factors related to sleep and physical activity.10) Cognitive decline also progresses more rapidly among spousal caregivers of individuals with dementia than among those caring for individuals without dementia.11)
Family members living with dementia patients are often spouses and older adults themselves.3) Caregiver burden may reduce their quality of life,12) which is closely correlated with that of the care recipients.13) Moreover, increased caregiver burden has been associated with an increased risk of institutionalization of dementia patients,14) which can place additional strain on the social care system. In an aging society, understanding the association between caregiving for family members with dementia and cognitive impairment in caregivers is essential for developing appropriate support systems for informal caregivers. However, existing studies have either been limited to specific geographic regions and focused solely on spousal caregivers,9,11) underscoring the need for broader research across diverse populations.
Therefore, this study aims to investigate the relationship between caregiving for family members with dementia and impaired daily activities due to cognitive decline among caregivers, using a large, nationally representative sample of family caregivers of individuals with dementia in Korea.
MATERIALS AND METHODS
Data and the Study Population
This cross-sectional study used data from the 2024 Korea Community Health Survey (CHS), a nationally representative survey of community-dwelling adults in Korea.15) The CHS is conducted annually by the Korea Disease Control and Prevention Agency. Sample households were selected using a stratified, clustered, systematic sampling method. All adults aged 19 years and older in the selected households were surveyed between May 16 and July 31, 2024. Trained interviewers conducted one-on-one, face-to-face interviews. This study included only individuals aged 50 years and older who have a family member with dementia (n=17,596) (Fig. 1).
Outcome Variable: Impaired Daily Activities due to Cognitive Decline
The dependent variable was self-reported impairment in daily activities attributable to cognitive decline. In the 2024 CHS, this was assessed using the question: “In the past year, how often have you been unable to perform routine household tasks due to confusion or memory loss? (e.g., cooking, cleaning, taking medication, driving, paying bills, etc.)” Participants who responded “always,” “mostly,” or “occasionally” were classified as “yes” (impaired), while those who answered “rarely” or “never” were classified as “no.”
Main Independent Variable: Cohabitation with a Family Member with Dementia
The key independent variable was whether the respondent cohabited with a family member with dementia. In the CHS, participants were first asked if any family member had been diagnosed with dementia by a physician. Those who answered “yes” were then asked whether they lived in the same household as that family member.
Covariates
Covariates included sociodemographic characteristics (sex, age group, education, marital status, employment status, and household income quartile) and health and behavioral factors (depression, perceived stress, physical activity, and sleep duration). Age was categorized as 50–59, 60–69, and ≥70 years. Education level was classified as no or primary education, middle school, high school, and college or higher. Marital status was categorized as married, divorced/separated/widowed, and single. Employment status was classified as self-employed, salaried, or economically inactive.
Depression was assessed using the 9-item Patient Health Questionnaire (PHQ-9). This screening tool asked respondents how often they had experienced specific symptoms over the past 2 weeks. Each item was rated on a 4-point Likert scale (1=never, 2=several days, 3=a week or longer, and 4=almost every day). Item scores were reduced by one, yielding a total score from 0 to 27. A score of 10 or higher indicated depression.
Perceived stress was included as a covariate because it is frequently used as an indicator of caregiver burden Family caregivers who experience chronic stress due to caregiving responsibilities may themselves be at increased risk of developing dementia.9) In the 2024 CHS, perceived stress was assessed by asking how much stress participants usually felt in daily life. Responses of “very much” or “much” were classified as stressed, while “slightly” or “rarely” were classified as not stressed.
Physical activity was defined as engaging in vigorous activity for ≥20 minutes on at least three days per week, or moderate activity for ≥30 minutes on at least five days per week. Sleep duration was categorized as <7 hours, 7 to <8 hours, and ≥8 hours per night, based on the National Sleep Foundation’s recommendation that adults aged 65 years and older obtain 7–8 hours of sleep per night.16)
Statistical Analysis
Study participants were described using frequencies and percentages according to their sociodemographic, health, and behavioral characteristics. The prevalence of impaired daily activities due to cognitive decline was estimated for each characteristic. The chi-squared test was used to assess if there is a difference in prevalence across categories of each characteristic. Multiple logistic regression analysis was conducted to examine whether cohabitation with a person with dementia was associated with an increased risk of impaired daily activities due to cognitive decline. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated.
All analyses accounted for the complex sampling design of the survey by applying sampling weights. Statistical analyses were performed using SAS version 9.4 (SAS Institute Inc., Cary, NC, USA).
The study protocol was reviewed and approved by the Institutional Review Board of Kongju National University (No. KNU_IRB_2025-100). Informed consent was waived by the ethics committee, as this study involved secondary analysis of publicly available data.
RESULTS
Among the 17,596 participants included in the analysis, 52.3% (n=9,542) were women, and 44.4% (n=6,330) were between 50 and 59 years of age (Table 1). A total of 72.6% had completed high school or college, 75.8% were currently married, and 42.4% were economically inactive. Overall, 5.6% of participants had depressive symptoms, and 22.2% reported experiencing stress. In addition, 22.2% engaged in regular moderate physical activity, while more than half (51.8%) slept fewer than 7 hours per day. Among all participants aged 50 years and older, 17.6% were cohabiting with a family member with dementia. Furthermore, 9.4% reported impaired daily activities due to cognitive decline.
The prevalence of impaired daily activities due to cognitive decline was 23.3% among individuals cohabiting with a family member with dementia, compared to 7.8% among those who were not (p<0.0001) (Table 2). The prevalence was also significantly higher among adults with depression (48.5%) compared to those without depression (8.3%), and among those who reported being stressed (18.3%) compared to those who did not (8.6%) (p<0.0001).
Among individuals with a family member with dementia, those aged 70 years or older were more than twice as likely to experience impaired daily activities due to cognitive decline compared with those aged 50–59 years (OR=2.50, 95% CI 2.03–3.08, p<0.0001) (Table 3). Individuals with no formal education or only primary education had higher odds of impairment compared with those with a college education (OR=1.64, 95% CI 1.33–2.03, p<0.0001). Those who were divorced/separated/widowed had increased odds of impairment compared with currently married participants (OR=1.84, 95% CI 1.61–2.10, p<0.0001).
People with depression were more than four times as likely to experience impaired daily activities, compared to those without depression (OR=4.85, 95% CI 4.00–5.87, p<0.0001). Perceived stress and lack of moderate exercise were also significant risk factors for impairment (both p<0.001). Both short (<7 hours) and long (≥8 hours) sleep durations were associated with increased odds of impaired daily activities. Cohabiting with a family member with dementia was associated with an increased risk of impaired daily activities due to cognitive decline (OR=1.86, 95% CI 1.63–2.12, p<0.0001).
DISCUSSION
Caring for individuals with dementia largely depends on informal caregivers, such as family members and relatives. With an aging population and the increasing prevalence of dementia, the role of informal caregiving is expected to become increasingly important. Family caregivers play a vital role in maintaining the quality of life of persons with dementia.16) Therefore, understanding the psychological and physical burden experienced by family members of individuals with dementia—many of whom may assume caregiving roles—is essential for sustaining the informal care system.
Using nationally representative data on Korean adults aged 50 years and older who had a family member with dementia, this study found that cohabiting with a family member with dementia was significantly associated with an increased risk of impaired daily activities due to cognitive decline. These findings are consistent with previous research focusing on spousal caregivers, suggesting that caregiving-related mechanisms may contribute to the observed associations.8-10) For example, a longitudinal study in the United States reported that spousal caregivers of individuals with dementia had a sixfold higher risk of developing dementia compared with spouses of dementia-free older adults.8) Similarly, spousal caregivers of persons with dementia experienced greater cognitive decline than spousal caregivers of individuals without dementia.10)
The link between cohabitation with a family member with dementia and cognitive decline in caregivers may be partly explained by caregiving-related physiological mechanisms. For example, a small-sample study reported that dementia caregivers had higher cortisol levels upon waking, and that perceived stress and poor sleep quality mediated the relationship between caregiving and cognitive function.17) A meta-analysis further showed that caregivers exhibit elevated stress hormone levels, such as cortisol, and reduced antibody responses compared with age- and sex-matched non-caregivers.18)
The challenges faced by family members of individuals with dementia may extend beyond the physical burden of care for those who assume caregiving responsibilities to include substantial emotional and psychological strain.19) This strain may be exacerbated by the prolonged duration of caregiving typically required for individuals with dementia. Consequently, family caregivers of individuals with dementia are more likely to experience physical and mental health problems than those caring for individuals with short-term medical conditions.20) A meta-analysis revealed that both the duration and intensity of caregiving are strongly associated with greater burden among family caregivers.21) Similarly, caregiver burden is negatively associated with caregivers’ rest hours while it is positively associated with behavioral problems in dementia patients.22) Collectively, these findings suggest that interventions offering respite from caregiving responsibilities may benefit family members who are engaged in intensive care roles.
However, caregiving burden and duration cannot fully explain the challenges experienced by family caregivers. For example, evidence regarding the effectiveness of home-based care interventions in reducing burden among dementia caregivers remains inconclusive.23) Furthermore, in the United States, family caregivers of dementia patients reported higher levels of physical and psychological strain compared to caregivers of patients with other conditions, such as diabetes or frailty, even after controlling for caregiving burden and duration.24) The heightened risk of cognitive decline among caregivers may be mediated by psychosocial and behavioral factors, including social isolation, depression, and reduced physical activity.9) Moreover, caregivers of individuals with dementia experience numerous unmet needs, including support for stress management and feelings of entrapment, as well as the need for respite from caregiving duties.25) Collectively, these findings suggest that interventions for family members of individuals with dementia may be most effective when they combine psychosocial support with opportunities for respite care. Existing literature supports this notion; interventions aimed at reducing caregiving burden and promoting caregivers’ mental health may help maintain their cognitive function.10) In addition, psychosocial interventions targeting family caregivers have been shown to reduce caregiver burden and delay institutionalization of dementia patients.16)
Existing literature has largely focused on spousal dementia caregivers and their increased risk of cognitive decline.8,10) In contrast, the present study expands the scope of potentially affected individuals to include all family members cohabiting with a person with dementia. However, due to limitations of the available data, it was not possible to determine whether these family members served as primary caregivers. Accordingly, the findings should be interpreted as reflecting the association between cohabitation with a family member with dementia and impaired daily functioning related to cognitive decline, rather than caregiving burden per se. While caregiving responsibilities may contribute to this association for some individuals, cohabitation alone may also entail psychosocial and environmental stressors that influence cognitive health.
Based on a large, nationally representative Korean sample, this present study shows that living with a family member with dementia is associated with impaired daily activities due to cognitive decline among caregivers. These findings suggest the importance of developing interventions to alleviate caregiver burden and promote caregiver well-being. However, this study has several limitations. First, the cross-sectional design limits the ability to infer causality. Second, the 2024 CHS dataset did not specify the exact relationship between the caregiver and the care recipient. Previous research suggests that the impact of caregiving on mental health may vary depending on the type of relationship (e.g., spousal vs. parent–child) and caregiver gender.26) Consequently, this study could not assess how the caregiver–care recipient relationship influences the association between cohabitation and impaired daily activities due to cognitive decline. In addition, a family history of dementia is a well-established risk factor for cognitive decline. Because the dataset did not allow us to identify genetically related family members or account for familial dementia risk, we could not disentangle caregiving- or cohabitation-related stress from potential genetic or shared familial susceptibility. Consequently, the observed associations may partly reflect unmeasured familial risk factors, and interpretations attributing the findings solely to caregiving or cohabitation effects should be made with caution. Last but not least, this study was based on self-reported measures of impaired daily activities due to cognitive decline, which highlights the need to explore more objective outcome measures in future studies. Future longitudinal research also is warranted to establish the temporal and causal relationships between cohabiting with a family member with dementia and cognitive decline among caregivers.
In conclusion, using a nationally representative sample of older Koreans, this study shows that cohabiting with a family member with dementia is associated with impaired daily functioning due to cognitive decline, even after adjusting for sociodemographic, health, and lifestyle factors. These findings highlight the need for policy measures and community-based support programs that monitor and promote the cognitive health of both individuals with dementia and their family caregivers.
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